Additive‐free Ethylene Dimerization over Well‐defined Nickel‐zeolite Catalysts

Ethylene dimerization is a crucial chemical process, which currently relies on organo‐metallic catalysis with the assistance of overdosed additives as cocatalysts. Heterogeneous nickel catalysts have been investigated as alternatives for ethylene dimerization, however suffer from low catalytic activity and/or poor 1‐butene selectivity. Herein, we report a simple two‐step ion‐exchange strategy for the preparation of Ni‐Mg‐Y zeolite containing well‐defined coordinatively‐unsaturated nickel centers as a promising catalyst for ethylene dimerization. Typically, Ni‐Mg‐Y shows unprecedent performance with 1‐butene formation rate of 3.8´105 h‐1 and 1‐butene selectivity of 91.2 %, comparable with the state‐of‐the‐art homogeneous and heterogeneous nickel catalysts but without the assistance of any cocatalysts. With the combination of advanced characterization techniques and comprehensive theoretical simulations, it has been demonstrated for the first time that the in‐situ generated Ni‐alkyl motif is the intrinsic active site and ethylene dimerization proceeds dominantly via the Cossee‐Arlman pathway. The dynamic hydrogen transfer between ethylene/alkyl ligand and zeolite framework dedicates to the observed catalytic performance, resembling of the role of cocatalyst in homogeneous nickel catalysis. This work not only provides an effective strategy for developing eligible catalysts for additive‐free ethylene dimerization to 1‐butene, but also offers valuable insights into bridging heterogeneous and homogeneous catalysis.